Fix the flaky KioskAppManageTest::RemoveApp and UpdateAndRemove tests flaky...

Fix the flaky KioskAppManageTest::RemoveApp and UpdateAndRemove tests flaky issue caused by file deletion racing condition.

BUG=373473

Review URL: https://codereview.chromium.org/290023005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271469 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc

@@ -551,7 +551,7 @@ IN_PROC_BROWSER_TEST_F(KioskAppManagerTest, RemoveApp) {
 
   // Remove the app now.
   manager()->RemoveApp(kTestLocalFsKioskApp);
-  content::RunAllPendingInMessageLoop(BrowserThread::FILE);
+  content::BrowserThread::GetBlockingPool()->FlushForTesting();
   manager()->GetApps(&apps);
   ASSERT_EQ(0u, apps.size());
   EXPECT_FALSE(base::PathExists(crx_path));
@@ -633,7 +633,7 @@ IN_PROC_BROWSER_TEST_F(KioskAppManagerTest, UpdateAndRemoveApp) {
 
   // Remove the app now.
   manager()->RemoveApp(kTestLocalFsKioskApp);
-  content::RunAllPendingInMessageLoop(BrowserThread::FILE);
+  content::BrowserThread::GetBlockingPool()->FlushForTesting();
   manager()->GetApps(&apps);
   ASSERT_EQ(0u, apps.size());
   // Verify both v1 and v2 crx files are removed.